The speed of Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) is closely related to the drive currents of the MOSFETs, which drive currents are further closely related to the mobility of charges. For example, NMOS FETs have high drive currents when the electron mobility in their channel regions is high, while PMOS FETs have high drive currents when the hole mobility in their channel regions is high.
Compound semiconductor materials comprising group III and group V elements (referred to as III-V compound semiconductors hereinafter) are good candidates for forming MOSFETs due to their high electron mobility. Therefore, III-V based MOSFETs have been explored recently.